This invention relates to an improved water reisitant seal for a watch case of the type having a lens with a peripheral edge to be sealed within a peripheral wall on the watch case bezel. More particularly, the invention relates to an improved water resistant seal using an elastomeric gasket.
Water resistant seals are well known which employ an elastomeric, or yielding, gasket which is forced between the peripheral edge of the watch lens or crystal and a groove in the bezel of the watch case to prevent moisture from entering the inside of the watch case. When the lens is circular, sealing is relatively easy to accomplish. However, sealing is much more difficult when the lens is rectangular or other non-circular shape. Variations in size due to normal manufacturing tolerances permissible in the lens or in the bezel become magnified in the event that a slightly oversized lens is assembled into a slightly undersized bezel opening, and vice versa. Watch designers have used a yieldable gasket to accomodate the variations. However, the compressive force on the gasket will also vary, leading to a leaking seal when an undersized lens is used with an oversized bezel opening. With very thin lenses of mineral glass or plastic, excessive pressures on the gasket to prevent leaking can lead to damage or breakage of the lens.
Prior art seals have been known which use elastomeric rings of circular cross section, which are squeezed in grooves between the edge of the lens and the bezel, sometimes being arranged to provide a downward force component on the lens to assist in the sealing. L-shaped gaskets are also known in which one leg of the "L" is compressed or squeezed radially or laterally between the bezel and the edge of the lens. The foregoing arrangements, however, are highly susceptible to variations in their effectiveness when the parts vary in size due to manufacturing tolerances.
Accordingly, one object of the present invention is to provide an improved water resistant seal which permits variations in component size due to manufacturing tolerances, while yet providing an effective seal.
Another object of the invention is to provide an improved water resistant seal using an L-shaped elastomeric gasket.